1. Technical Field
This disclosure relates to polymeric compositions. More specifically, this disclosure relates to stereoregular polypropylene and methods of producing same.
2. Background
Olefin polymers and copolymers such as polyethylene, polypropylene and ethylene-propylene can be produced under various polymerization conditions and employing various polymerization catalysts. In the case of C3 or greater alpha olefins, the resulting polymer may exhibit stereoregularity. For example, in the case of propylene, a polypropylene product may be isotactic wherein each methyl group attached to the tertiary carbon atoms of the successive monomeric unit falls on the same side of a hypothetical plane through the main chain of the polymer. Polypropylene may also be syndiotactic wherein the methyl groups attached to the tertiary carbon atoms of the successive monomeric unit are arranged as racemic dyads. In other words, the methyl groups in isotactic polypropylene lie on the same side of the polymer backbone whereas in syndiotactic polypropylene the methyl groups lie on alternate sides of the polymer backbone. In the absence of any regular arrangement of the methyl groups with respect to the polymer backbone the polymer is atactic.
Various factors influence the utility of a polymer product. For example, the stereoregularity of the polymeric product impacts both the physical and mechanical properties of said product. Additional factors that affect the utility of the polymer product include the melting temperature, crystallinity and melt flow rate. The combination of these and other factors determine the suitability of the polymer product for a particular plastics shaping process. Thus, a need exists for improved stereoregular polymeric materials designed for high performance in plastic shaping processes.